The current state of the art includes four different types of simple measuring devices and spirometers:    Peak flow or maximum flow measuring devices, that do not measure the ventilatory function; their use is limited to home monitoring of this parameter for a single patient for asthma but not for any other respiratory diseases.    Peak flow electronic measuring devices, with or without FEV1 measurement (Forced Expiratory Volume in the first second). These devices do not measure the ventilatory function and their use is the same as simple measuring devices with the advantage that they are more precise but not very accurate, and that they also can store and calculate variability. The ATS (American Thoracic Society) recommends a PEF (peak expiratory flow) maneuver for peak flow monitoring different from the conventional FVC maneuver, from which the FEV1 is obtained. This PEF maneuver consists of a sharp and sudden forced exhalation from a position of maximal inspiration reaching maximum flow normally in one tenth of a second, depending on the effort and volume, and not allowing the FEV1 to be obtained.
The above-mentioned measuring devices—in spite of being affordable—do not allow screening, spirometric diagnosis, follow-up of ventilatory disorders or valuation of variability or functional situation in pathologies different from asthma, as in the case of chronic obstructive pulmonary diseases.
Other presently available spirometers are:    Monitoring spirometers to measure the ventilatory function; they are portable and allow a trained patient to evaluate and monitor their ventilatory function by means of FVC maneuvers, and some also use inspiratory maneuvers. These spirometers, in spite of their reduced size and handling, have not been designed to adapt to the various clinical situations where it is necessary to measure ventilatory functions such as the case in pharmacies, emergency rooms, hospitals or clinics, use by subjects that are untrained or with little ability, or subjects suffering from coughing, dyspnea, and/or intense bronchial obstruction    Laboratory spirometers designed to measure the ventilatory function and to carry out studies in Centers by qualified personnel. A great disadvantage of these spirometers is their high cost and the requirement for calibration and disinfection systems that make them only accessible to certain professionals, specialized centers and hospitals. With these devices it is not possible to measure the various types of functional variability as they do not allow monitoring and therefore they cannot be used for diagnosing the type of asthma and/or chronic bronchitis that the patient presents with nor the response to treatment.
Simple measuring devices for respiratory parameters such as peak flow and FEV1 do not measure the ventilatory function in spite of being more affordable than monitoring and laboratory spirometers. Although the latter do measure ventilatory function they do not adapt themselves to the various clinical situations where the determination of this function is necessary.
Spanish patent, ES2073542, requested by GLAXO AUSTRALIA PTY., LTD. describes an electronic measuring device that only measures two parameters: the volume expired in one second in liters, and the expiratory peak flow rate. With these parameters it is not possible to completely and accurately determine the ventilatory function.
French patent FR2729072 requested by FRANCOIS JEAN, also describes a measuring device similar to the previously described one, and measuring the same parameters. This device can be used in several medical applications; however, it provides no option to customize different clinical situations.
Application PCT, WO97/18753, requested by TIUS ELCON LTD., describes a measuring device similar to the aforementioned ones for home monitoring of asthma; its main application is monitoring the response to the patient's medication. This device calculates the best value measured over a period of time, several days of measurements, determined by the patient himself as a base, without the assistance of an expert. This does not provide a reliable baseline result to be compared with subsequent measurements.
As indicated above, the ventilatory function cannot be measured at present in most situations where this is required, contrary to the case for determining the blood glucose level and blood pressure. For this reason and according to all studies published, respiratory conditions such as asthma or chronic obstructive pulmonary disease—which are as or more frequent than diabetes or arterial hypertension—are not detected early, are not properly diagnosed, are underestimated and are treated incorrectly, thus resulting in high morbidity, mortality and health care costs that could be avoided.
VC and FEV1 are two excellent health markers, as important as, or even more than, blood pressure, glucose, cholesterol or weight; however, nobody knows their VC or FEV1 or what these values mean.
The multispirometer and the method to measure ventilatory function by spirometry as described below, overcomes the problems posed by existing measuring devices and spirometers.